Applicant claims priority under 35 U.S.C. xc2xa7119 of GERMAN Application No. 199 41 306.1 filed Aug. 31, 1999. Applicant also claims priority under 35 U.S.C. xc2xa7365 PCT/DE00/02808 filed on Aug. 16, 2000. The international application under PCT article 21(2) was not published in English.
1. Field of the Invention
The invention relates to a roller chain for continuously guiding and/or stretching the width of a web of textile material on a machine stretching a web of textile material (the so-called tenter). The roller chain comprises inside and outside members which are connected via chain joints in a successively alternating manner,
(a) whereby each inside member is comprised of two inner tabs as well as two sleeves connecting the inner tabs with each other, and each outer member is comprised of two outer tabs as well as two bolts connecting the outer tabs with each other;
(b) whereby each sleeve is coaxially mounted and rotatably supported on the associated bolt;
(c) whereby coaxially on the outside on the sleeve, provision is made for a running roller as the outer ring of a ball bearing that is to be supplied with lubricant via a lubrication channel extending through the interior of the bolt;
(d) whereby the ball bearing comprises an inner ring coupled with the sleeve, and located on each end a sealing ring resting coaxially against the ball bearing; and
(e) whereby the inner tabs are unmovably pressed onto the sleeve and axially against the inner ring of the ball bearing via a space-keeping element bridging the sealing ring in terms of transmission of force.
2. Prior Art
A roller chain with said features is part of the internal prior art of the applicant firm. The invention in particular relates to a further development of the sealing ring of the roller chain specified in item (d) above.
EP 0 400 375 B2 describes a roller chain in connection with which the lubrication channel for the ball bearing is leading directly into the interior of the ball bearing via an inner tab. In the known art, the lubrication channel is disposed about parallel with the axis of the bolt outside of said axis. Such a structure simplifies the re-lubrication of the chain because the channel of the lubricant for re-lubricating the ball bearing follows a substantially straight course from the point of lubrication where the lubricant is injected into the channel, up to the actual bearing. However, the point of lubrication where the lubricant is injected on the outer side of the respective inner tab is located near the bolt. The outer tab is axially seated on the bolt outside of the inner tab. In some chain constructions, the free end of the outer tab projects far (in the longitudinal direction of the chain) beyond the inner tab to such an extent that the area available for placing the point lubrication for injecting the lubricant is substantially covered by the outer tab. For re-lubrication, the outer tab would then have to be either shortened or provided with a drilled hole. Such an expenditure is not justifiable, as a rule.
Conventional lubrication channels are used for the lubricant, if need be, for example such as the lubricant channels described in DE 35 29 683 A1. According to said patent, the ball bearings of the chain links are lubricated from the interior of each bolt. For this purpose, provision is made in each chain bolt for an axial longitudinal bore with a radial branch leading to the ball bearing. The sleeve and the inner ring of the ball bearing have an opening located in a site which, when the bearing is lubricated, has to be brought to coincide with the radial branch mentioned above. This means that the radial branch of the longitudinal bore of the bolt and the channel leading through the sleeve have to be aligned with one another. If the sleeve is connected with the associated pair of inner tabs in a fixed manner, and the bolt is connected in a fixed manner with the adjacent pair of outer tabs, such a passage channel can be provided in terms of construction in a manner such that, for example in connection with a chain stretching in a straight line, the bores and the passages are aligned from the point of lubrication where the lubricant is injected, up to the interior of the ball bearing.
In connection with modern roller chains of the type specified above, the tabs, which have a bore located at each longitudinal end, are pressed with their bores onto the associated sleeve in the direction of the ball bearing, and riveted to the sleeve, if need be. In such a pressing process, the force is directly transmitted to the inner ring of the ball bearing located adjacent to the sleeve. If a sealing ring has to be mounted on the interior space of the ball bearing containing the balls and the lubricating grease, a ring made of metal, for example such as bronze or steel, is inserted in practical applications between the axial longitudinal end of the inner ring of the ball bearing and the inner tab. Such a ring, which functions as a space-keeping element, creates the force-free space for accommodating the sealing ring. In such an embodiment, the spacer ring and the sealing ring are thus successively arranged, radially starting from the sleeve. The spacer ring serves the purpose of transmitting to the inner ring of the ball bearing the axial forces occurring when the inner tab is pressed over and riveted to the sleeve. One purpose of the sealing ring is to substantially protect the interior of the ball baring against any unintended loss of lubricant.
If, with a chain construction of the type described above that comprises inner tabs riveted to the respective sleeves, one wanted to extend the lubrication channel starting from the interior of the ball bearing up into the interior of the ball bearing, the lubrication channel would have to extend through the spacer ring, which means gaps would be required in the ring accordingly. The dimensions that could be considered possible in such a case would require a division of the spacer ring. However, it is difficult when the sleeve and the inner tab are joined by pressing and riveting to bring a gap provided in the spacer ring in exact coincidence with a lubricant bore provided in the sleeve.
The invention is based on the problem of improving the spacer ring in such a manner that the problems arising when aligning a re-lubrication passage with the radial branch of the bolt and the passage in the sleeve, are overcome, and that the transmission of the forces exerted as the inner tab is being pressed over and, if need be, riveted to the sleeve, is nonetheless assured without impairing the function of the sealing ring.
For the roller chain specified above, the solution according to the invention consists in that the sealing ring is substantially made of plastic and unrotatably coupled with the adjacent inner tab; that the spacer in the form of individual metallic inserts, which are approximately equally distributed over the bolt in the circumferential direction, is integrated in the sealing ring; that each insert extends approximately axially through the sealing ring, whereby the overall cross section of all inserts measured in the plane of the ring is small as compared to the surface area of the ring; and that the surface of the sealing ring facing the ball bearing comprises at least one lubrication groove that connects the lubrication channel of the bolt and a lubrication hole of the sleeve with the interior of the ball bearing as a passage for the lubricant, with the lubrication hole of the sleeve being brought to coincide with the lubrication channel of the bolt. Improvements and other embodiments of the invention are also disclosed.
The inserts preferably have a hardness in the order of magnitude of the hardness of the material of the sleeve and the inner tab. In particular, the inserts may have the hardness of steel. The inserts may be integrated in the form of balls or cylinders or also of cubes or square blocks. It is of primary importance that each individual insert is at least as thick in the axial direction (based on the sealing ring) as the sealing ring itself (which may be slightly pressed, if need be). This applies in particular to the area of the sealing ring that is axially disposed between the longitudinal edge of the inner ring of the ball bearing and the inner tab. It has been found in tests that four or more inserts equally distributed in the sealing ring over the radius of the inner ring of the ball bearing are adequate for transmitting the forces occurring during the pressing and, if necessary, riveting process. Provision has to be made for at least three inserts in order to assure that the sealing ring is in a defined position in the course of the pressing and riveting process.
The objective achieved with the invention is that the actual axial connection of force can be secured during the pressing and riveting process without impairing the lubrication connection extending transversely, i.e. radially in relation to such an axial connection of force, because adequate space remains available between the individual metallic inserts of the sealing ring for a lubrication channel or a lubrication groove that forms the connection between the radial branch of the longitudinal channel of the bolt and the interior of the ball bearing. In practical life, the installation may be simplified if the sealing ring comprises a plurality of, for example two diametrally opposed lubrication grooves located on its inner side facing the ball bearing. It needs to be noted in this connection that the individual lubrication groove on the sealing ring, when viewed radially in relation to the axis (of the bolt), is required only in that area of the ring where the spacer inserts are installed, i.e. the lubrication grooves, on their radial way outwards, end on a barrier that prevents any normal loss of lubricant, but assures that lubricant is directly transported from the groove or on the barrier into the interior of the ball bearing.